http://www.parktool.com/blog/repair-...ewheel-removal

You will need to determine the style of hub you have and the style or brand of cog system. The table below shows several different options.


FR-1
Shimano® freewheel
12 splines, approx. 23mm diameter



FR-2
Older Suntour® two notched, 25mm across
FR-3
Suntour® four notched, 24mm across



FR-4
Atom® and Reginia®
20 splines, approx dia. 21.6mm


FR-5, or FR-5G with guide pin
Shimano® cassette lockring, Sun Race®, Hugi®, many brands
12 splines, approx. 23.4mm diameter



FR-6
BMX and Freestyle one-speed 4-notch freewheels-
4 notches, 40mm across



FR-7
Falcon® brand freewheels-
12 splines, approx 23mm diameter



BBT-5/FR-11Campagnolo cassette lockrings-(for Campagnolo cassettes, not freewheels)
12 splines, approx. 22.8mm diameter
FR-8
Compact single speed(30mm thread, "flip-flop hubs")
There may be older model freewheels where a tool is no tool available. It may still be possible re-use the wheel but at the loss of the freewheel. There are also current models of freewheels that do not have an adequate design for removal. If the image below, the freewheel has two very narrow and shallow notches that do not allow enough purchase for a tool. Removal of this type of freewheel would likely result in ruining the tool, the freewheel, or both. For either situation, see destructive removal of freewheels


This model of freewheel has no removal tool fittings of any type.